Theoretical Study of Hydrogen Effect in Diamond Film Growth

为了阐明CVD法在室温常压下生长金刚石薄膜的原因，并从计算物理的角度研究新材料的晶体生长机理，我们着重讨论了氢气气氛对金刚石生长的必要性。我们采用准静态的方法对氢封端金刚石表面上吸附原子从上方移动到二聚体中心的体系进行了优化。结果表明，随着吸附原子的吸附，终止氢原子从表面上移除，并终止了吸附原子的悬挂键。这个过程显示了碳原子的表面活性剂效应。这些结果与硅表面的情况进行了对比。我们从碳原子更倾向于sp^2键而硅原子更倾向于sp^3键的事实，以及碳、硅原子相对于氢原子的电子亲合势关系e_c&gt;e_H&gt;e_来解释这些结果<Si>。

To clarify the reason why the growth of diamond film is achieved under the room temperature and atmospheric pressure by CVD method, and to study the mechanism of crystal growth for new meterials from the view point of computational physics, these are the aim of the research.We focused our attention to the necessity of hydrogen atmosphere for the diamond growth. We optimized the system, in which the adatom is moved from above to the center of the dimer on hydrogen-terminated (100) diamond surface, in a quasi-static way. The results shows that the terminating hydrogen atom removes from the surface, as the adatom adsorbs, and terminates the dangling bonds of the adatom. This process shows the surfactant effect of the carbon atom. These results are contrasted with the case of silicon surface. We interpreted the results from the facts that the carbon atom prefers sp^2 bonding whereas the silicon atom prefers sp^3 bonding, and the relation of electron affinities of carbon and silicon atoms relative to hydrogen atom, e_c>e_H>e_<Si>.